my name is Dupree and i drive a 1991 suburban i swaped out my 91 motor with a 95 tahoe motor with a 700r4 trans so..im loseing power slow take off and i can go as fast as 65 mph foot to the floor timeing is set perfect. so why no power? should i change the plugs? is it a fuel issue? or is the 700r4 the wrong trans or should i put a computer from a 95 tahoe in it also it back fires i was reving the engine and a ball of fire shot out please help CHEVY GODS!!!

 

I believe the 5.7 comes with the 4L60e trans. and given that it is a 95 engine you should have a 95 comp ecm in it

 

thanks sledgehammer so swap it out and power comes back?

 

it can be done but ....here is a better explanation I found:

You need a 4L60E. emphasis on the "E". It is electronic, it supplies information to and receives information from the computer that is used to manage the fuel injection, ignition timing among a host of other things.

GM and confusion:they are so great at this!

The 700R4 is a mechanically controlled, overdrive version of the old TH350, but it does output some digital age data for the vehicle's computer management system. The 700R4 went thru a long gestation where it had many in-service problems. GM finally got them worked out and when they did they renamed the thing 4L60 (no "E"). The 4L60 from the era of 1990 to about 93 is still a mechanically controlled transmission that furnishes some rocket science to the computer but is not on the receiving end from the computer.

Then comes 4L60E, remember the "E" for electronic. These start phasing in around 1994, they have all the 700R4 fixes making them mechanically a 4L60! But wait! GM took out the mechanical, hydraulic controls and put in electronic, hydraulic controls so now this thing not only talks to the computer, but listens for instructions as well. Holy cow-a-bunga!!!

On top of this; your 95 is several feet inside the OBD II generation of really highly integrated computer management systems and your engine has sequential fuel injection instead of the old TPI or even cruder TBI batch fire systems.

Trust me, unless your a masochist, it's way easier to just spend the extra thousand bucks and get a 4L60E put back. Yes you can back date to a 700R4 or 4L60, it'll just cost 2 to 3000 dollars more than what you've already spent and take a couple, three months to debug the car and get everything working if it ever works correctly. You have to remember with a 700R4/4L60 in there you no longer have a vehicle that is an engineered consumer product, you have for want of a better term, a hot rod.



(This is from a different forum. if you do a google search there is actually a ton of info on this subject)

 

you da man!!!